1. Field of the Invention
The invention relates generally to a new hygienic treatment method for dental care in which a laser toothbrush is employed on a regular schedule with lightly photosensitized liquids or paste to achieve and maintain a reduction in bacteria in the oral cavity while minimizing side effects of photosensitizers.
2. Invention Disclosure Statement
Generally in the prior art mechanical cleaning of teeth with manual, electric and/or water jet devices is of a superficial nature only and does not penetrate into the skin-tissue or into pockets to remove or destroy bacteria and viral contamination. Additionally, normal dental paste is of very limited effect in terms of bacterial and viral destruction. Low power laser bio-stimulation produces enzymes which can destroy viruses and bacteria present on teeth, in the mouth, on the gums and below the gum line. Consequential inflammation and pain is also eliminated. The radiation must be provided with pulsed diode laser at varying repetition rate frequencies to selectively trigger the body's natural defense to infection within the mouth. Optimum effect can be achieved with GaAs (Gallium Arsenide) pulsed diode laser at a width of 200-300 nsec, .lambda.=904 nm, power=5-10 mW, application time 1-3 minutes. Three different repetition rate frequencies can be used to treat different dental conditions as follows:
F1=73 Hz for Parodontitides, dental pain PA1 F2=292 Hz for Gingivitis, stomatitis PA1 F3=584 Hz for Gingivitis, stomatitis paradontophaties PA1 (a) Zn (II) phthalocyanine is activated at .lambda.=670 nm PA1 (b) Si (IV) naphthalocyanine is activated at .lambda.=780 nm PA1 (c) Pd (OBu).sub.8 naphthalocyanine is activated at .lambda.=820 nm
It is known through research in the area of photodynamic therapy that certain substances are created as a byproduct of laser radiation. These substances contain atomic or singlet oxygen that is believed to destroy tumor cells. Similarly, atomic oxygen resulting from laser radiation can enhance destruction of oral bacteria and viruses. Research has been conducted and reported which teaches that gram-positive and gram-negative bacteria are sensitive to singlet oxygen generated by a physically separated photosensitizer. Thus, laser radiation will destroy oral bacteria. [See, e.g., Giuliana Valduga et. al., "Effect of Extracellularly Generated Singlet Oxygen on Gram-positive and Gram-negative Bacteria," J. Photochem. Photobiol. B. Biol., 21 (1993) 81-86.]
The wavelength at which the diode laser of the system is operated is related to the specific photosensitizer used. A photosensitizer such as a Phthalocyanine can be activated by continuous wave diode laser as follows:
These methods and practices need to be performed by trained professionals, thus they cannot be part of a routine dental hygiene approach. They are both cost and time prohibitive because they must be done in a dental practitioners office.
Besides the phthalocyanine photosensitizers, described above, other sensitizers such as methylene blue are used for PhotoDynamic and similar therapies. For example in Wilson et al., U.S. Pat. No. 5,611,793, a large number of chemical which disinfect or sterilize tissues within the oral cavity and are activated by laser light are described and their relative efficiency of action measured.
Generally as in U.S. Pat. No. 5,611,793 the treatment, as with the earlier described laser treatments, is provided by a professional frequently in combination with some dental surgical procedures. Highly active materials are used to provide for quick treatment times or else intense sources are needed to allow professionals to see multiple patients in a given working period. The need for dental practitioners is due primarily to two major safety problems. First, because of the intensity of coherent laser light the possibility for accidental injury arises from misapplication or misdirection of the laser output. Temporary or permanent damage to unprotected eyes can occur as well as `burning` of healthy tissue instead of attack on diseased tissue only. Tissue damage can occur because the photosensitizers while somewhat selective usually are taken up by healthy tissue as well as diseased tissue. Secondly, ingestion of these sensitizers, accidental or otherwise, creates potential for serious side effects such as `sun burning` of the skin upon exposure to normal sunlight or even bright lights. Often significant levels of the photosensitizer need to be associated with a treatment site for the PDT process to be effective. Should a patient swallow a significant amount of the photosensitized material they would have to restrict their exposure to daylight for a period of a few hours to a few days to allow time for the photosensitizers to be expelled from normal tissue and eventually the body. For general use by the public, accidental ingestion by a child would be an added safety concern. These safety concerns are now ameliorated by requiring the use of trained dental practitioners generally in a remote site for such treatments. It would be a gain in the public's dental care if the benefits of such processes could be made more wide spread.
In addition multiple treatments with photosensitizers, which are at the levels needed for PDT treatments and which actively absorb light in the visible region of the spectrum, can lead to incorporation of the colored segments into the enamel or dentin. While there are many bleaching compositions and methods available, see e.g. Cornell U.S. Pat. No. 5,032,178 they can be time consuming or require careful application.
The present invention presents methods to avoid or ameliorate these problems by providing safe, simple methods for improved dental care by the `patient` consumers themselves. The methods and devices described herein provide a general dental hygiene program which allow the public user to maintain better oral hygiene with reduced bacterial and microbial contamination within the oral cavity, and thus to enjoy the health and other benefits arising from the cleaner oral environment.